Broadband ISDN using asynchronous transfer mode as the transport mode carries traffic of several different classes, including one or more real-time traffic classes, each with its own set of traffic characteristics and performance requirements. To support multiple classes of traffic in ATM networks, multiple priority levels are provided, and different priority levels are given to different classes of traffic. A dynamic priority scheme is proposed as an efficient scheduling method at a switching node in an ATM network serving multiple classes of delay-sensitive traffic. The advantage of this protocol lies in that, by properly adjusting the control parameters, it can meet the average delay requirement for different classes and thus guarantee the quality of service. In addition, each class of service can be guaranteed a minimum of bandwidth, which can prevent the low priority class from starvation.